Field of the Invention
Embodiments of the present invention relates to a printed circuit board, and a lighting device and backlight unit including the printed circuit board.
Description of the Related Arts
According to the development of electronic device industries, various display devices have been developed, and an image device, a computer, a mobile communication terminal and the like using the display devices have been also developed. A liquid crystal display device which appeared according to this trend is catching on as a display device such as a monitor, a mobile communication terminal and the like.
A liquid crystal display (LCD) is based on applying electrical and optical properties of liquid crystal having an intermediate property between liquid and solid to a display device, and serves to convert various kinds of electrical information generated from various devices into a visual information from using a variation in transmittance of the liquid crystal according to an applied voltage to transmits the information. The LCD is a widely used flat display because it has low power consumption due to its low operating voltage and is a conveniently portable device.
Since the LCD has no self-luminous property for emitting light itself, a backlight is always needed for all the LCDs. The backlight serves as a light source of the LCD, and a backlight unit is a complex that forms a power circuit for drive of the light source as well as the light source for irradiating light to a rear surface of a liquid crystal module and all appendages which enable uniform flat light to form. As a light source for illuminating the LCD, the backlight unit using a light emitting diode (LED) has been recently suggested. The LED is a lighting emitting device which generates light using a light emitting phenomenon generated when a voltage is applied to a semiconductor. This LED has a small size and long lifespan compared to the conventional light source. Furthermore, since the LED directly converts electrical energy into light energy, it has high energy efficiency and a low operating voltage.
As the liquid crystal display device configured as above becomes gradually slimmer, it has been needed to reduce a width of the liquid crystal display device. Accordingly, in order to reduce the width of the liquid crystal display device, a size of the backlight unit which has an effect on the width of the liquid crystal display device should be reduced. The size of the backlight unit can be reduced by reducing a pad part or a string part of a printed circuit board.
FIG. 1 is a view illustrating a printed circuit board according to a conventional art.
Referring to FIG. 1, the printed circuit board (PCB) includes a pad part 50 in which a plurality of light emitting devices 40 like LEDs are mounted, and a string part 60 in which a string wiring connected to the light emitting devices 40 and for transmitting an electric signal to the light emitting devices 40 is formed.
When bending treatment is performed for the printed circuit board, an insulating substrate or the string wiring within a bending part 70 formed between the pad part 50 and the string part 60 is damaged such as being ripped or pressed. Due to this damage, a defect in electricity or appearance occurs, thereby causing damage to the printed circuit board.
Accordingly, by forming the bending part not to have damage thereto and efficiently forming a wiring of the printed circuit board, a way for reducing a height of the liquid crystal display device has been needed.